1. Field of the Invention
This invention relates to an apparatus for transporting a web of a flexible material between a first and a second position. In particular, and in a preferred embodiment, the invention provides an apparatus, known as a xe2x80x9cvacuum conveyorxe2x80x9d, for transporting a web, preferably a lead strip (or xe2x80x9ctailxe2x80x9d) of a paper web, e.g. from the dryer of a paper-making machine to the first nip of a calender of the machine or to a winding machine or between any other sections of a paper-making or paper-finishing (e.g. coating) machine.
2. Discussion of Background Information
A vacuum conveyor is known from DE 26 36 887 which is similar to U.S. Pat. No. 4,022,366. Conveyors of this kind have proven successful in operation. In some applications, however, the lead strip must be deviated (in a known manner) out of the area of the web width into the area of a rope system which is outside the web width, for threading the lead strip through the following machine-section. For this purpose, the conveyor is arranged in an oblique position so that its downstream end is positioned in the area of the rope system outside the web width. A problem is that immediately after the transfer of the beginning of the lead strip into the rope system, the following main part of the lead strip shall travel again in its area inside the web width. Therefore, only the beginning of the lead strip must positively cling to the conveyor""s belt. Immediately thereafter the lead strip should have only a loose contact to the conveyor. For that purpose one tries to rapidly decrease the degree of vacuum applied to the conveyor. But that does not always work in a reliable manner, in particle with the high operating speed of modern paper machines.
U.S. Pat. No. 4,692,215 discloses a vacuum conveyor cooperating with a rope system which again is positioned outside the web width. The vacuum conveyor is adjustable around a vertical axis which is arranged at the upstream pulley of the conveyor, so that the tail can be directed into the rope nip.
However, this document does not disclose any details how to control the adjustment or movement of the conveyor around the vertical axis. Such a control should be very precise because the transfer of the beginning of the tail into the rope nip must go on with the normal machine speed (up to about 2000 m/min), i.e., within a period of about 1 second or less. Moreover, U.S. Pat. No. 4,692,215 does not disclose any details how to support the vacuum conveyor with respect to the axis.
Therefore, the invention is based an the problem of further developing the known vacuum conveyor in such a way that the transfer of a lead strip into a following machine section is improved, in particular at high operating speeds.
According to a first aspect of the invention, the belt conveyor can be pivoted xe2x80x94immediately after it has transferred the beginning of a leading strip into a rope system from an oblique position into a straight, forward position, whereby it moves the lead strip into the area of the web width, so that, the conveyor now reliably transfers the main part of the lead stripxe2x80x94within the area of the web widthxe2x80x94into the following machine section. In summary, the transfer of the lead strip from the preceding to the following machine section will be significantly improved, even at high operating speeds.
According to a second aspect of the invention, a vacuum conveyor is supported by a connecting structure which connects the conveyor with a rotatable support. The rotatable support includes a rotatable bearing housing which is fixed to the connecting structure, with at least one bearing being arranged within the bearing housing and being supported by a stationary central stub or by a stationary central section of the vacuum line. This design is very compact and very easy to integrate into any type of paper machine. This is due to the fact that the rotatable support includes a base plate, e.g., only one, for connecting the rotatable support to a machine frame. It is therefore a universal pivot which is applicable not only with the vacuum conveyor designed according to the first aspect, but also with various other vacuum conveyors. The pivot axis may be arranged, e.g., vertical but outside the web width in order to remove the conveyor out of the machine. In a different embodiment, the pivot axis may be arranged parallel to the pulley""s axes in order to vary the working direction of the conveyor.
According to a third aspect of the invention, the vacuum conveyor is again connected to a rotatable support. The connecting structure is now formed as a vacuum channel. Therefore, it has two functions, namely to support the vacuum conveyor as well as to connect it to the vacuum source. This novel design is space-saving and the manufacturing costs are low.
The present invention is directed to an apparatus transferring at least a portion of a running web from a first section of a web making machine to a second section of the web making machine arranged downstream from the first section, relative to a web run direction, the second section including a portion adapted to receive a full width of the running web and a rope section located outside of the full width receiving portion. The apparatus includes a belt conveyor which includes at least two pulleys, in which at least one is a driven pulley, an air-pervious endless conveyor belt tensioned over the at least two pulleys to form a conveying run and a return run, and a device for creating a negative pressure at an inner surface of the conveying run. The at least one driven pulley being adapted to drive the endless conveyor belt over the at least two pulleys while the negative pressure propagates through the conveying run. The belt conveyor also includes an upstream and a downstream end and the belt conveyor is pivotable around a pivot axis located in a region of the upstream end. The apparatus is pivotable to move the portion of the running web between the rope section and the portion is adapted to receive a fall width of the running web. The apparatus also includes a control system for moving the downstream end into an area of the web width when a beginning of the at least a portion of the web has entered the rope section.
According to a feature of the instant invention, a rotatable support, which is rotatable around the pivot axis and a connecting structure, may be adapted to support the apparatus. The connecting structure can couple the conveyor apparatus to the support. The rotatable support may be connected to a stationary structure by a motor for pivoting the apparatus. Further, the rotatable support can include a rotatable bearing housing which is fixed to the connecting structure, and at least one bearing may be arranged within the bearing housing and is supported by a stationary central stub.
In accordance with another feature of the present invention, the at least a portion of the running web includes a threading tail, and the running web includes a paper web.
According to still another feature of the invention, the pivot axis can be at least approximately vertical to a plane of a belt run direction.
The invention is also directed to an apparatus for transferring at least a portion of a running web including a belt conveyor that includes at least two pulleys, in which at least one is a driven pulley, an air-pervious endless conveyor belt tensioned over the at least two pulleys to form a loop, and a device for creating a negative pressure within the loop. The negative pressure is sufficient to draw the at least a portion of the running web onto the endless conveyor belt. The at least one driven pulley is adapted to drive the endless conveyor belt over the at least two pulleys, such that the negative pressure propagates through the conveyor belt. The apparatus also includes a connecting structure and a rotatable support which rotates around a pivot axis are provided, and the connecting structure couples the belt conveyor to rotatable support. The rotatable support includes a rotatable bearing housing fixed to the connecting structure, a stationary central stub, and at least one bearing, and the at least one bearing is arranged within the bearing housing, which is supported by one of the stationary central stub and a stationary central section of a vacuum channel.
According to a feature of the invention, at least one bearing can include a pair of tapered antifriction bearings, the bearing housing can be coupled to the stationary central stub by the pair of tapered antifriction bearings, and the rotatable bearing housing can be fixed in both axial directions relative to the stub. Further, at least one sealing device can arranged between the housing and the stationary central stub. An interior of the bearing housing may be completely closed to an outside atmosphere.
In accordance with another feature of the present invention, the at least a portion of the running web comprises a threading tail, and the running web comprises a paper web.
According to a further feature of the instant invention, the pivot axis can be about parallel to an axis of the first and second pulleys.
In accordance with still another feature of the invention, the rotatable support can be connected to a stationary structure by a motor for pivoting the endless conveyor.
The present invention is also directed to an apparatus for transferring at least a portion of a running web including a belt conveyor that includes at least two pulleys, in which at least one is a driven pulley, a suction box coupled to a vacuum source, and an air-pervious endless conveyor belt tensioned over the at least two pulleys. The suction box is located within a loop of conveyor belt and is positioned to create a vacuum sufficient to draw the at least a portion of the running web onto the endless conveyor belt. The at least one driven pulley is adapted to drive the endless conveyor belt over the at least two pulleys and over the suction box. The apparatus also includes a rotatable support that is rotatable around a pivot axis, and a connecting structure is adapted to couple the belt conveyor with the rotatable support. The connecting structure includes a vacuum channel that couples the suction box to the vacuum source.
In accordance with a feature of the present invention, the apparatus can further include a stationary structure, a stationary vacuum chamber, and the rotatable support can include a rotatable bar having at least one end. The at least one end of the rotatable bar can be supported in a bearing coupled to the stationary structure, and positioned to extend through the vacuum chamber. The vacuum chamber can be fixedly coupled to the connecting structure and to the rotatable bar, such that the vacuum chamber is rotatable. The rotatable bar may be positioned to extend through the stationary vacuum chamber which is open to an interior of the rotatable vacuum chamber, and the stationary vacuum chamber can be coupled to the vacuum source. Further, the pivot axis can be at least approximately vertical to a plane of a belt run direction.
The present invention is also directed to a process for transferring at least a portion of a running web from a first section of a web making machine to a second section of the web making machine arranged downstream from the first section, relative to a web run direction, the second section including a portion adapted to receive a full width of the running web and a rope section located outside of the fall width receiving portion with a belt conveyor. The belt conveyor includes at least two pulleys, in which at least one is a driven pulley, a device for creating a negative pressure, an air-pervious endless conveyor belt tensioned over the at least two pulleys, and the device for creating the negative pressure creating the negative pressure within a loop of the belt conveyor. The belt conveyor includes an upstream and a downstream end and the belt conveyor is pivotable around a pivot axis located in a region of the upstream end. The process includes rotating the endless conveyor belt by driving the at least one driven pulley, creating a negative pressure at an inner surface of the endless conveyor belt as the endless conveyor belt is traveling over the pulleys, and guiding the at least a portion of the running web onto the endless conveyor belt. In this way, the at least a portion of the running web is suctioned onto the endless conveyor belt. The process also includes transferring the at least a portion of the running web from the endless conveyor to the rope section located outside of a web width, pivoting the endless conveyor belt around the pivot axis to move the downstream end into an area of the rope section one of at and before the transferring, and pivoting the apparatus including the endless conveyor belt around the pivot axis to move the downstream end into an area of the at least a portion of the running web and inside the web width.
According to a feature of the instant invention, the pivoting to move the downstream end into an area inside the web width may begin at a selectable time after the beginning of the transferring.
In accordance with another feature of the present invention, the pivoting to move the downstream end into an area inside the web width may begin when a beginning of the at least a portion of the tail arrives at a selectable point located in a downstream section. The downstream section can be a calender. Further, a detecting device can detect the beginning of the at least a portion of the tail arriving at the selectable point.
According to yet another feature of the invention, the process can further include pivoting the endless conveyor belt around the pivot axis to position the downstream end adjacent the portion adapted to receive the full width of the running web.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.